Shaft Couplings 119
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d:\N-Design\Des7-1.pm5 Seventh Print
0.2 D
1.5 D
1.25 D
1.1 D
0.7 D
0.3 D
33
0.3 D 0.3 D2DD0.75 D
Fig. 7.6 Solid flanged coupling7.3 Flexible Couplings
Perfect alignment of two shafts is impossible to achieve and difficult to maintain, because of
inevitable bearing wear and other reasons. To overcome the trouble, flexible couplings are
employed. These permit relative rotation or variation in the alignment of shaft axes within
certain limits. The following are the types of flexible couplings:
7.3.1 Bushed Pin Type Flanged Coupling
It is the modified version of a protected flanged coupling. In this, bolts are replaced by bushed
pins. The smaller ends of the pins are rigidly fastened by nuts to one of the flanges, while the
enlarged ends are covered with flexible material like leather or rubber bushes, in the other
flange (Fig. 7.7). The flexible medium takes care of mis-alignment, if any, and acts as a shock
absorber. These couplings are used to connect prime mover or an electric motor and a centrifugal
pump.
DT1.75D
W1.75D0.85 D4 HOLES, DIA 0.6 D0.7 D
0.3 D0.5 D0.5 D0.3 D
30.7 D4 HOLES,
DIA 0.3 D52.25 D(a)0.5 D 0.4 D0.6 D 0.3 D0.2 D 0.5 D0.8D + 3 0.3 DFig. 7.7 Bushed pin type flanged coupling (Contd.)